What do the characters in an SAP t-code mean?

I am new to SAP. Can anyone please explain what the characters in a SAP t-code mean if there is any meaning to the code. I've seen t-codes like SU01 and assume that the SU stands for "Super User" so any t-code beginning with SU specifies transactions performed by the system admin or super user while those beginning with M has something to do with fixed assets?? Can anyone kindly clarify what these characters mean? Thank you.